DESIGN KONTROL ON-OFF PADA PROSES PENGERINGAN BUNGA ROSELLA

Pemanfaatan Kelopak Bunga Rosella sudah dikenal dan diteliti baik oleh pakar kesehatan modern maupun pakar kesehatan tradisional di berbagai negara di dunia. Kelopak bunga tersebut diketahui mengandung zat-zat penting yang diperlukan oleh tubuh, seperti vitamin C, vitamin A, protein esensial, kalsium, dan 18 jenis asam amino. Disamping tanaman ini merupakan tanaman hias, ternyata tanaman ini banyak sekali manfaatnya untuk kesehatan tubuh, sehingga banyak sekali orang yang memanfaatkan peluang ini dengan memproduksi dengan cara mengeringkan kelopak buga rosella melalui sinar matahari secara langsung untuk dijadikan minuman seduhan (teh). Namun seringkali timbul masalah dalam proses pengeringan khususnya dimusim hujan, temperatur tidak menentu seperti saat ini. Dengan berubah-ubahnya temperatur mengakibatkan proses pengeringan tidak bisa terbentuk tepat pada waktunya dan kualitasnya berkurang, sehingga diperlukan sistem yang dapat mengatur temperatur utamanya pada saat proses pengeringan tersebut.Dalam penelitian ini dirancang bangun prototype pengatur temperatur pada proses pengeringan kelopak bunga rosela, dimana pada proses ini dibutuhkan temperatur yang stabil yaitu antara 50oC sampai 60oC . Untuk pengaturan tersebut dipilih kontrol on-off yang disetting dan dipadukan elemen pemanas dengan menggunakan thermo couple, sehingga diharapkan pengaturan temperatur dapat terkontrol pada setingan tersebut.Hasil pada penelitian ini adalah berupa terbangunnya model prototype yang optimal, selain itu model ini dapat dipakai sebagai acuan pada tempat lain, sedangkan tujuan jangka panjang dari penelitian ini adalah untuk pengembangan Ipteks khususnya untuk Home industri Teh Rosella.

Basic Study on Thermo Chemical Turning Method for Metal Bonded Diamond Wheels

In this paper, a new truing method is proposed instead of the conventional mechanical truing that has low truing rate for metal bonded diamond grinding wheels. In the proposed method, the metal-bond diamond grinding wheel is rubbed by a steel truer rotating at high speed. Generated frictional heat increases the oxidization and the diffusion of carbon into the steel truer, then diamond grains are thermally attrited on the wheel surface, so that the machinability of wheel is improved. Subsequently, high truing rate is achieved by mechanical truing with abrasive stones. These experiments are conducted using bronze bonded diamond abrasive stones and stainless steel truers, and the relation between truing resistance, truing temperature, and truing rate are investigated. The truing temperature is measured using the thermo couple embedded in the truer. The thermo couple consists of the steel wire embedded and the bronze which is the bonding material of the abrasive stone. The surface profiles of abrasive stones are measured by scanning stylus before and after truing, then the removal volume of abrasive stones is derived from these profiles. Truing rate is also obtained from the removal volume and the truing time. Experimental results for diamond abrasive stones are as follows: The waviness of bronze bond is decreased by proposed truing method. Truing rate is increased as truing resistance and truing temperature increase.

Impact of stitch length on sewing needle temperature

In this article the sewing needle heat is measured without sewing thread and with sewing thread at different stitch density (stitches per inch or SPI) of lock stitch sewing machine by thermocouples. Two methods are used to measure sewing needle heat, touch thermocouple method and inserted thermo couple method. Needle temperature is measured after periodic 10, 20, 30 and 60 seconds of sewing operation. Whereas the machine running at speed from 1000 r/m to 4700 r/m. It is observed that decreasing stitch length causes an increase in the temperature of the sewing needle. Stitch density shows same influence on needle for sewing with thread and without thread. It is observed from our research that at SPI of 14 the needle temperature with thread rises to 259 °C at 4000 r/min of machine. It is recommended to use minimum stitch density.

The Study of Pavement Surface Temperature Behavior of Different Permeable Pavement Materials during Summer Time

This study explored the thermal behavior of permeable pavement during summer. T-type thermo-couple needle was utilized to measure the surface temperature of three different permeable pavement materials. Data were measured based upon the 24 solar terms of the traditional Chinese lunisolar calendar and the results of Great Heat in comparison with other solar terms showed significant differences. Heat output model calculation results show that the average heat output is the lowest for grass bricks because of its high reflectivity. This material has a cooling effect, followed by permeable interlocking bricks. Permeable asphalt concrete can reduce pavement temperature but there were limitations to its performance.

Effects of Radiation on Temperature Measurement in a Fire Environment

Thermocouples have been widely used to measure temperature in research and industry. For the purpose of building fire experiments, the thermo couple has been and will be a major instrument to obtain the temperature field of the fire environment, and hence to quantify the intensity of building fire. It has been found that the radiation error significantly affects the measured tempera ture using thermocouples. However, this issue has not been carefully investigated in the area of building fire research. A suction pyrometer was designed and applied to a series of fire experiments in a full-scale experimental building-fire facility to avoid the effect of radiation on the measured temperature. It was found that the reading from a bare thermocou ple could be more than 100°C higher than the gas temperature obtained from the suction pyrometer during the flaming fire stage and more than 200°C higher dur ing the flashover stage. For a steady-state fire environment obtained from a propane gas burner fire, the radiation error was negligible in the hot upper level near the ceiling. However, the thermocouple significantly overestimated the gas temperature by more than 80°C in the cool lower level near the floor because of the radiation error. The tem perature predicted by the computational fluid dynamics model, CESARE-CFD fire model, was in good agreement with the measured temperature after the ra diation correction in the lower level and deviated slightly in the upper level.